U.S. Pat. No. 8,721,287 B2 has disclosed an impeller of the generic type for an exhaust gas turbocharger having a hub main body and blades which are arranged thereon. In order for it to be possible here to reduce the load, in particular in an attachment region of the blades to the hub main body, a transition between the hub main body and the blades is rounded in the manner of an ellipse.
In general, impellers consist of a hub main body and the blades which are arranged thereon, modern impellers usually being equipped for thermodynamic reasons with a backward curved impeller outlet. Under the influence of the centrifugal force on a suction side in the attachment region of the blades to the hub main body, said backward curvature leads to high tensile stresses which reduce the expected service life. A higher rotational speed and/or an even more pronounced backward curvature are/is possible only to a restricted extent, however, for reasons of the service life. Moreover, the hub main bodies which are usually used nowadays are configured as continuously round rotational bodies, this simple geometry not being ideal with regard to the load which occurs particularly at a transition between the blade and the hub main body. This can also be remedied here only to a limited extent by way of an increase in a radius at the transition between the blade and the hub main body, since the highest load often does not occur at the transition itself, but rather in the hub main body at the end of the transition.